Molded plastic splice casing with combination cable anchorage and cable shielding grounding facility

ABSTRACT

A cable splice casing cast in two mating halves from high strength plastic material and equipped with one or more conductive anchor assemblies for mechanically and electrically connecting the cable shield and sheath jackets to each end of the casing while the latter is open. The casing acts to interconnect the cable sheath across the splice area and to provide electrical continuity between the respective cable shield jackets. A heavy gauge conductor along the interior of the casing interconnects the cable anchor assemblies located at the opposite ends of the casing to carry heavier electrical charges whereas a conductive liner for the splice casing provides electrical shielding for the portion of the cabling exposed for making splice connections. The anchorages are spaced inwardly of a sealing gasket at each end of the casing and the latter can be opened for servicing and testing without disturbing the cable anchorage or the grounding connection between the cables and the casing.

Unite States te Thompson et al.

[ Notice:

The portion of the term of this patent subsequent to Oct. 19, 1988, hasbeen disclaimed.

[22] Filed: July 27, 1971 21 Appl. No.: 166,386

Related U.S. Application Data Continuation-in-part of Ser. No. 12,819,Feb. T9?

1970, Pat. No. 3,614,298.

Santa Monica, Calif. 90405 ]*Mar. 19, 1974 Primary Examiner-Darrell L.Clay Attorney, Agent, or Firm-Sellers and Brace 1 5 ABSTRACT A cablesplice casing cast in two mating halves from high strength plasticmaterial and equipped with one or more conductive anchor assemblies formechanically and electrically connecting the cable shield and sheathjackets to each end of the casing while the latter is open. The casingacts to interconnect the cable sheath across the splice area and toprovide electrical continuity between the respective cable shieldjackets. A heavy gauge conductor along the interior of the easinginterconnects the cable anchor assemblies located at the opposite endsof the casing to carry heavier electrical charges whereas a conductiveliner for the splice casing provides electrical shielding for theportion of the cabling exposed for making splice connections. Theanchorages are spaced inwardly of a sealing gasket at each end of thecasing and the latter can be opened for servicing and testing withoutdisturbing the cable anchorage or the grounding connection between thecables and the casing.

T2 Dra wing Figures Fm. a, v M

INVENTOR5- g nlaia ig l MOLDED PLASTICSPLKCE CASING WITH COMBINATIONCABLE ANCHORAGE AND CABLE SHIELDING GROUNDHNG FACILHTY This applicationis a continuation-in-part of our copending application for U. SLI-tat.Ser. No. 12,819 filed Feb. 19, 1970, now U.S. Pat. No. 3,614,298.

Thisinvention relates to cable splice assemblies and more particularlyto improved means for enclosing a splice zone with a protectivenon-metallic splice casing having means for completing a high strengthmechanical and electrical connection between the cable sheath and shieldjackets and readily accommodating one or two cables at either end of thecasing.

Multiple conductor communication cables are used in countless numbers incommunication networks and have need for frequent splice connectionswith one another and with branchout cable lines. The completion of suchsplice connections necessitates removal of a length of the protectivesheath and of the underlying electrical shield jacket to expose theconductors. These conductors are not intended to carry any substantialportion of the cable load and this is especially true as respectsspliced conductors which must be isolated from such tensile stresses.For this reason it is important to provide a suitable strongload-carrying connection to the cable sheath as well as a positiveelectrical connection between the shield jackets to either end of thesplice zone.-

ltis becoming increasingly common to employ splice zones with anon-conductive protective casing cast or molded in two semi-cylindricalhalves securable together along their mating edges. However, the designsheretofore proposed for this purpose are subject to numerousshortcomings and disadvantages sought to be avoided by the presentinvention. Thus such proposals have inadequate or no provision to anchorthe cable to either end of the splice to the splice casing or to shieldthe spliced wires from ambient electrical fields.

Another serious problem attending the use of devices heretofore proposedto anchor and ground cable shielding jackets to one another between theopposite ends of the splice housing a problem which is accentuated whenusing splice housings formed 7 of nonconductive material.

It is therefore a primary purpose of the present invention to provide asimple improved cable anchorage and grounding assembly for use in spliceassemblies avoiding the foregoing and other shortcomings of priordesigns. The invention anchorage utilizes a pair of metal I shoes and aclamping screw insertable through an opening in the sidewall of thecable shield and sheath and effective to hold the latter rigidly clampedtogether. The threaded screw used for the clamping operation is theninserted through an anchorage strap straddling the cable in an areainside one end of the splice casing and having its ends rigidlysecurable to the splice casing to either side of the cable. Thisanchorage strap is formed of strong metal and is deeply arched so as tostraddle cables of various diameters and is sufficiently strong totransmit substantially the full tensile strength of the cable sheath tothe splice casing. Additionally this metal anchorage provides a positivehighly-reliable electrical connection between the cable shield and ametallic lining or coating fixed to the interior surface of the moldedplastic splice casing. This lining or coating provides a highlyeffective electrical shield for the casing is provided with pairs oflongitudinally offset seating supports in electrical contact with theaforementioned metallic layer and selectively usable as the cableanchorages. At least one set of these seats is preferably offsetinwardly from the open face of the casing thereby adding materially tothe versatility of the splice casing and to accommodate cables of widelyvarying diameters or two or more cables of the same or differentdiameters. The cable anchor straps are also preferably provided with aplurality of openings in any one of which the threaded stud clamped tothe cable sheath can be inserted. thereby compensating for tolerancevariations, contraction and shrinkage of the cable sheath and othervariables. Additional current carrying capacity for the cable shield isprovided by a heavy gauge bonding strap extending along the interior ofthe splice casing and having its ends detachably clamped to the archedanchorage strap for each cable.

As will be recognized from the foregoing, the invention anchorages areinstalled on the cable sheath and shielding jacket and then clamped toone of the casing halves while the other half is detached. After theseparts have been installed the operator may thoroughly check theinstallation both mechanically and electrically before securing thecover half in place.

It is therefore a primary object of the present invention to provide anew and improved cable splice assembly featuring a molded plastic casinghaving provision for anchoring an electrical cable thereto.

Another object of the invention is the provision of a cable splicecasing formed primarily of molded plastic composition and having anelectrical shielding layer fixed thereto with provision for connectingthe same in circuit with the shield jacket of each cable served by thesplice casing.

Another object of the invention is the provision of a plastic splicecasing with a built-in electrical shield for the spliced conductors andheavy duty means interconnecting the shield jackets of cables enteringthe splice casing.

Another object of the invention is the provision of an improvedlightweight non-metallic cable splice casing with a built-in electricalshield extending substantially from end to end thereof.

Another object of the invention is the provision of an improvednon-metallic cable splice casing formed in separable halves havingsimple, highly effective mechanical and electrical anchorage meansreadily connectable to either a cable sheath or shield jacket or to bothwithout placing the conductors themselves under stress or strain.

These and other more specific objects will appear upon reading thefollowing specification and claims and upon considering in connectiontherewith the attached drawings to which they relate.

Referring now to the drawing in which a preferred embodiment of theinvention is illustrated:

FIG. 1 is a side view of a typical embodiment of the invention spliceassembly installed about a cable splice;

FIG. 2 is a longitudinal elevational view on an enlarged scale throughone end of the assembly shown in FIG. 1 and showing the front half ofthe splice casing detached;'

FIG. 3 is a cross sectional view along the broken line indicated at 3--3on FIG. 2 but showing the forward casing half in assembled position;

FIG. 4 is a cross sectional view taken generally along line 4-4 on FIG.2 and showing parts of the anchor assembly broken away; I

FIG. 5 is a cross sectional view taken along line 5-5 on FIG. 2;

FIG. 6 is a view similar to FIG. 2 but showing the cable anchor meansinstalled in an alternate position;

FIG. 7 is a cross sectional view taken along line 77 on FIG. 6;

FIG. 8 is a view similar to FIG. 6 but showing two small cablesinstalled in the casing with each anchored to a different portion of thesplice casing,

FIG. 9 is a cross sectional view taken along the broken line 9-9 on FIG.8;

FIG. 10 is a view similar to FIG. 8 but showing a different mode ofanchoring a pair of cables to the splice casing;

FIG. 11 is a fragmentary cross sectional view on an enlarged scale takenalong line l1-11 on FIG. 10; and

FIG. 12 is a fragmentary cross sectional view on an enlarged scale ofthe upper end portion of FIG. 3 and showing more clearly details of theconductive liner or coating for the interior surfaces of the splicecasing shown in FIGS. 1 to 11.

Referring initially and more particularly to FIGS. 1 to 5, there isshown a typical embodiment of the invention splice case assemblydesignated generally 10, installed over a splice between two alignedcables 11,12 entering its opposite ends. The splice case comprises apair of cast or molded semicylindrical halves 14,15 having radialflanges 16,17 projecting from their opposite sides and releasablyclamped together by cap screws 18. Each of the casings 14,15 is formedof high strength non-conductive plastic material of which there arenumerous suitable compositions well known to those skilled in theplastics art. The juxtaposed surfaces of flanges 16 and l7 are providedwith mating channels seating a sealing gasket 20 in accordance withcustomary practice.

Additional sealing means for forming a hermetic seal between the casinghalves and cabling entering their opposite ends is best shown in FIG. 4.Thus, the reduced diameter inlet collar at either end of the casing isformed with a pair of inwardly directed annular recesses 23,24 seatinggasket rings or washers 25,26 flanked from suitable flexible insulatingmaterial, such as sheet plastic. These gasket rings are formed withopenings sized to fit snugly about the particular cabling entering thesplice casing and include a radial slit 27 running from the openingthrough one edge of the gasket, and facilitating the assembly of thegasket ring to the cable. The space between rings 25,26 is filled withsuitable sealing material such as a plastic buna tape or cording whichis sufficiently plastic as to be readily distributed to fill the cavitybetween rings 25,26 despite the fact the'cable is offset verysubstantially to one side of the center of these rings.

The combination electrical and mechanical anchorage interconnecting thecable sheath and the splice casing, designated generally 30, comprisestwo principal sub-assemblies, the first including the componentsattached firmly to the cable shield and electrical shield,

and the second including means interconnecting this first sub-assemblyto the splice casing and to the conductive shielding layer or coating 31(FIG. 12) suitably bonded to the interior surfaces of casing halves14,15 substantially fron end to end thereof. Thin metal foil or aconductive coating is applied to all interior surfaces to provide acomplete shielding jacket having its opposite ends overlapping the cableshield jackets 35. In consequence there is no gap in the shielding forthe conductors even though it is necessary to break into the cableshield jacket in order to splice the conductors together. FIG. 12 alsomakes clear that conductive layer 31 extends between the mating flanges16,17.

The above mentioned first sub-assembly includes a threaded shank 32having its inner end fixed to an arcuate metallic shoe 33. Preferably aresilient metallic shim 34, supported by shoe 33, is formed with sharptangs which penetrate any insulative film which may be present on thecable shielding jacket 35. It will be understood that this electricalshielding jacket is of the customary type surrounding the cableconductors and underlying the thick insulative sheath 36 of the cable.The threaded shank 32 extends through aligned openings formed in shield35 and sheath 36 and then through an opening centrally of a metalclamping shoe 38 conforming to the external contour of the cable. Theassembly of shank 32 from the inner ends of these aligned mountingopenings is preferably performed in the manner disclosed in detail inour copending application for U. S. Pat., Se'r. No. 12,820, filed Feb.19, I970. The portion of the cable to either side of shank 32 is thenserved with snug convolutions of strong pressure sensitive tape 39 priorto the assembly of the outer clamping shoe 38. Thereafter, the clampingshoe is inserted over shank 32 and securely clamped in place by clampingnut 42.

From the foregoing it will be recognized that tightening of the clampingnut 42 serves to compress inner shoe 34 and outer shoe 38 against theintervening electrical shield jacket 35 and cable sheath 36 therebyproviding an extremely high strength mechanical connection to these twolayers as well as an electrical connection between shoe 33, shieldjacket 35 and shank 32.

The second anchorage or companion sub-assembly comprises a heavy gaugemetal strap 44 having an arched portion 45 interposed between oppositelydirected ends 46 formed wih openings for clamping screws 47,47. Screws47 seat in threaded bores 48 (FIG. 3) formed in flanges 16,16 of casinghalf 14 and opening into shallow recesses 49. The threaded bores areformed in metal inserts 50 molded into the casing halves. Anchor strap44 is preferably provided with aligned projections 52 projecting fromits opposite lateral sides and formed with a series of holes 53 any oneof which may be assembled about threaded shank 32 of the first describedanchor sub-assembly and clamped tightly in place by a nut (FIGS. 3, 4).As is best shown in FIG. 4, the splice casing is formed with shallowwells or detent means 54 aligned with openings 53 and adapted to looselyreceive the outer end of shank 32. It will therefore be evident thatirrespective of which of openings 53 is used to accommodate shank 32 theouter end of the shank will extend into one of the wells 54. It will beunderstood that these wells or detents cooperate with the shank instrengthening and stabilizing the anchor assembly in response to tensionforces commonly acting along the cables entering the ends of the splicecasing.

Referring now to FIGS. 6 and 7, the described anchorage assembly 30 isshown installed in the same splice casing to provide an electrical andmechanical anchorage between a much larger cable and casing half 14. Inthis particular installation however, the ends 46 of the cable anchoragestrap 44'are supported on a pair of bosses 60 formed integral withcasing half 14 in an area spaced axially inwardly of mounting recesses49 .on which the strap is shown supported in FIGS. 1-4. Each of thesebosses isformed with a threaded well 61 in a metal insert similar toinsert 50 described above. It will be'noted from FIG. 7 that the upperends of bosses 60 are coplanar with one another and located in a planespaced substantially below the level of the mounting surfaces 49. Thisarrangement not only facilitates the accommodation of a considerablylarger cable but also permits a small diameter cable to enter the sameend of the splice housing as will be described presently in connectionwith FIGS. 8 and 9. it will be understood that the cable shield andsheath are anchored to strap 44 by a clamping sub-assembly of the sameconstruction described above in connection with FIGS. 1-5 and that aportion of the conductive layer 31 (FIG. 12) is clamped between insert50 and the end of strap 44.

Referring now to FIGS. 8 and 9, the splice casing and anchorage isshownin use with two cables l2a,ll2b of relatively small diameter enteringthe same end of the splice casing in closely spaced side by siderelation. Separate identical anchorage assemblies to those describedabove are employed for the respective cables. As shown, the anchoragesare installed on the remote sides of the two cables l2a,l2b with thearched portion of the two straps facing toward one another andpositioned for the securement of their ends to a respective set of thethreaded wells 48,48 and 61,61. Thus, the arched portion of theanchorage for cable 12a faces upwardlyor to the left as viewed in FIG.9, whereas the corresponding anchorage strap 44 for cable 12b underliesthis cable as shown in FIG. 8 with its outer ends secured to bosses 60by anchor screws 47.

The cables enter the splice casing through appropriately contouredgaskets 25,26 and the plastic packing material 28 is distributedtherebetween in a manner completely filling the space between the cable,gaskets 25,26 and the interior side walls of the end portions of thesplice casing to provide a hermetic seal.

Referring now to FIGS. and 11, there is shown one manner in which asingle anchor strap 44 can be employed to anchor a pair of smallerdiameter cables l2c,l2d to splice casing half 14. In this case theanchor subassemblies providing an anchorage connection to each of thecable shields and sheaths are installed on a portion of each of thecable sheaths located substantially inwardly of the inlet ends of thecasing halves 14, 15 as for example forwardly of anchor bosses 60,60. Asshown, anchor strap 44 is secured in place in clamping recesses 49following which its midportion is rigidly connected to the threadedshanks 32,32 by metal straps 64,65 each provided with closely spacedholes. A hole at the inner ends of each strap is secured to a respectivethreaded shank, as .by clamping nuts 66, and the other ends are securedby a common nut and bolt assembly 67,68 to one of the holes 53 in anchorstrap 44. Desirably the outer ends of bolts 68 project into one of theshallow wells 54' in cover half 15 and serve to strengthen and stabilizethe adjacent portions of the anchorage assembly. 7

Another feature of importance preferably provided in each of the abovedescribed constructions is a supplemental heavy duty bonding strap bestshown in FIGS. 2 and 3. This strap is similar to conductive straps 64,65just described in connection with FIGS. 10 and 11 but is employed toprovide a heavy duty conductive path between the anchor straps 44 whichhave such an excellent electrical connection to each cable shieldjacket. To this end bonding straps 75 are tightly but separably anchoredto straps 44 by cap screws 76 mating with threaded bores in straps 44.It will be under stood that straps 75 are formed of ductile conductivematerial and are readily shaped by finger pressure to lie closelyagainst the interior surface of the conductive layer 31. Although notillustrated in all views, it will be understood that the heavy capacitybonding straps 75 are preferably present in all variants of the presentinvention and are so located as not to interfere with the spliceconnections or the opening and closing of the splice casing halves.

While the particular molded plastic splice casing with combination cableanchorage and cable shield grounding facility herein shown and disclosedin detail is fully capable of attaining the objects and providing theadvantages hereibefore stated, it is to be understood that it is merelyillustrative of the presently preferred embodiment of the invention, andthat no limitations are intended to the details of construction ordesign herein shown other than as defined in the appended claims.

We claim:

1. A cable splice casing formed in two mating halves from tough highstrength plastic material and including means holding said halvessecured together in a fluidtight manner, said casing having cable inletopenings at its opposite ends, means for sealing said casing halvesclosed about cabling insertable through said cable inlet openings, eachof said casing halves including a layer of conductive material extendingsubstantially the length of said casing and adapted to overlap theshield jacket of shielded cables adjacent the interior ends of saidcable inlet openings, threaded wells opening into the interior of saidcasing inwardly of either end thereof and located along the oppositesides of said cable inlet openings, an arched conductive anchor strapextending crosswise of the interior of said casing at each end thereofand including threaded clamping screw means anchoring the opposite endsthereof to a respective one of said wells and in conductive relation tothe conductive layer of said casing half, and metallic cable clampingmeans securable to an opening through a respective cable shield jacketand the overlying portion of a cable sheath and including meansanchoring the same to the adjacent one of said anchor straps.

2. A cable splice casing as defined in claim 1 characterized in theprovision of a heavy gauge conductor extending lengthwise of theinterior of said splice casing and having its ends connected to arespective one of said cable anchor straps and providing high-strengthhigh-capacity bonding connections electrically interconnecting saidcable anchor straps.

1. A cable splice casing formed in two mating halves from tough highstrength plastic material and including means holding said halvessecured together in a fluid-tight manner, said casing having cable inletopenings at its opposite ends, means for sealing said casing halvesclosed about cabling insertable through said cable inlet openings, eachof said casing halves including a layer of conductive material extendingsubstantially the length of said casing and adapted to overlap theshield jacket of shielded cables adjacent the interior ends of saidcable inlet openings, threaded wells opening into the interior of saidcasing inwardly of either end thereof and located along the oppositesides of said cable inlet openings, an arched conductive anchor strapextending crosswise of the interior of said casing at each end thereofand including threaded clamping screw means anchoring the opposite endsthereof to a respective one of said wells and in conductive relation tothe conductive layer of said casing half, and metallic cable clampingmeans securable to an opening through a respective cable shield jacketand the overlying portion of a cable sheath and including meansanchoring the same to the adjacent one of said anchor straps.
 2. A cablesplice casing as defined in claim 1 characterized in the provision of aheavy gauge conductor extending lengthwise of the interior of saidsplice casing and having its ends connected to a respective one of saidcable anchor straps and providing high-strength high-capacity bondingconnections electrically interconnecting said cable anchor straps.